Can an MML eliminate the need for a SYE?
- Thread starter JMT
- Start date
The MML is going to lift the engine, therefore slightly changing the angle of the transfer case (pushing it at more of a downward angle), and thus allowing the pinion angle to be less extreme. If you had a 2" lift and were getting some vibrations, you may be able to get rid of them with just a MML. However, if you're running 4" of lift, an MML alone won't get rid of the vibrations. You're going to need a SYE at that height regardless.
OP
Yes, DC, for some reason everyone just says CV. Thanks for the correction!
I think I'm just scared off more than anything from the SYE and DC because of the folks on here who have driveline vibes for whatever reason (can't get pinion angle correct, who knows???) I hear you though, I was concerned that with that much MML I might hit the tub. Of course, Tim at Brown Dog sells up to a 2" MML. I'm not sure what application they have, but it's a special application, for sure. Theoretically, I was thinking it might eliminate the need for SYE and DC. I've got an e-mail in to the man himself. So I'll report back his response...
After adding my Currie 4" lift, I put my DC driveshaft on and dialed in the pinion angles perfectly the first time. The front one doesn't need to be adjusted, and the rear was as easy as using a digital angle finder and then making sure the rear pinion was 1-2 degrees lower than the driveshaft angle. It's really not even hard at all, honestly. This is coming from someone (me) who has never adjusted driveline angles before in my life.
Don't let my vibe issues scare you from it. My vibes are likely as a result of something else and hope to find the culprit so a SYE and DC driveshaft is a solid plan. You might also want to consider other wear factors of other components after installing a MML that tall. Steering column linkage, throwing things off balance, etc.
OP
Yeah, Tim responded to my inquiry. Here's his response...
"So many questions. You should NOT use a 1.5 or larger MML on this set-up at all. You could do damage to the driveline. With only a 2.5 suspension lift, you should be using stock height motor mounts at this point. In the range of suspension lifts, we consider a 2.5 in the same category as “no lift” because the effect is negligible.
An SYE and CV should not be a consideration with a 2.5 in lift as far as driveline angles go.
One other question: Why are you considering a tummy tuck on this set-up?"
"So many questions. You should NOT use a 1.5 or larger MML on this set-up at all. You could do damage to the driveline. With only a 2.5 suspension lift, you should be using stock height motor mounts at this point. In the range of suspension lifts, we consider a 2.5 in the same category as “no lift” because the effect is negligible.
An SYE and CV should not be a consideration with a 2.5 in lift as far as driveline angles go.
One other question: Why are you considering a tummy tuck on this set-up?"
Not in all cases. When I installed my OME 2.5" lift, I had terrible rear drive line vibes, and ended up having to lower my TC skid 3/4" to eliminate the vibes. Would a MML helped my situation? Maybe, maybe not.
True, most people just drop the transfer case in that situation. But a MML may have.
OP
That's what I told Tim. I had vibes at 2.5" and so I added the TCase drop. After a couple of months I ordered his 1"MML and I was able to remove the TCase drop. So it solved my vibes problem...
There are a number of ways, only one way to do it correctly.
OP
Every TJ seems to be different. As stated, the definitive way to go is a sye and dc shaft. MML, tc drops, are really just a band aid. That said, I used a 1" mml on 2.25" lift and it worked for my set up.
OP
Yeah, it’s no guarantee there won’t be other problems. I’m sure a solid install with solid parts and no other issues that might interact unwontingly would be perfect. Maybe I’m being silly by being scared off.
With adjustable rear arms to dial in the pinion angle.
It may not be a 100% guarantee but if you bring me 100 rigs to fix that problem on, I can do it on at least 99 of them. Of that 99, 90 of them will be cake and 9 of them will be a PITA but we'll get it. We've only had one that was problematic enough that we had to put a hub kit on the front to get rid of vibes. I know of a couple more like that but not that I've worked on personally.